bpo-29776: Use decorator syntax for properties. (#585)

diff --git a/Lib/multiprocessing/dummy/connection.py b/Lib/multiprocessing/dummy/connection.py
index 1984375..f0ce320 100644
--- a/Lib/multiprocessing/dummy/connection.py
+++ b/Lib/multiprocessing/dummy/connection.py
@@ -26,7 +26,9 @@
     def close(self):
         self._backlog_queue = None
 
-    address = property(lambda self: self._backlog_queue)
+    @property
+    def address(self):
+        return self._backlog_queue
 
     def __enter__(self):
         return self